1. Field of the Invention
This invention relates generally to the field of seismic prospecting, and more particularly, to a method and apparatus for injecting an acoustic pulse.
2. Description of the Prior Art
In Applicant's co-pending, commonly assigned applications, Ser. No. 3,107,009 filed Dec. 21, 1979 entitled Acoustic Pulse Generator, truck-mounted apparatus is described wherein gas pressure may be employed to propel an impact piston downwardly against a target plate located adjacent the lower end of the housing. The compressed gas is provided by one or more accumulators and introduced through large area ports in the sidewall of the housing which are normally blocked by the wall of the piston in its upper firing position. Initial downward displacement of the piston in opposition to spring bias clears the ports and exposes the face of the piston to the gas pressure, thus driving the piston downward to deliver a blow to the target.
The invention to be described hereafter represents an improvement on the method and apparatus of the above prior application which is particularly concerned with means for more efficiently exploiting compressed gas as a driving force in an impact device of this character.
It is therefore a general object of the present invention to provide an acoustic pulse generator of the type described with improved mass acceleration means.
It is a more particular object of the present invention to provide improved means for applying pressurized gas as an energy source in an acoustic pulse generator of the type described.
Other and further objects and advantages of the invention will become apparent from a consideration of the detailed description and drawings to follow.